Semiconductor devices having recent increased performance and speed may employ a structure that effectively radiates heat generated in semiconductor chips to the outside. For example, it is known to provide a plate-like member having good radiation on a semiconductor chip. In order to suppress warpage of a substrate on which a semiconductor chip is mounted, there are known a structure in which a reinforcement member is provided on a substrate and another structure in a substrate and a plate-like member provided on a semiconductor chip are bonded together by a reinforcement member (see Japanese Laid-Open Patent Publication No. 2007-165433, International Publication Pamphlet No. WO2005/024940, and Japanese Laid-Open Patent Publication No. 2004-260138, for example).
In order to improve the bonding strength between a semiconductor device and a mounting board such as a mother board, an underfill agent may be injected between the semiconductor device and the mounting board. In this case, it has been proposed to provide a frame-like member on the mounting board, the frame-like member being configured to contain an underfill agent and have a seal that is provided to an opening through which the underfill agent is caused to flow out and peels off at a predetermined temperature (see Japanese Laid-Open Patent Publication No. 2006-261545, for example). According to this publication, the seal that seals the underfill agent is heated to the predetermined temperature or higher for separation, whereby the underfill agent is injected between the semiconductor device and the mounting board. It has also been proposed to use, as the underfill agent injected between the semiconductor device and the mounting device, a member having a decreased bonding strength when the member is heated to the predetermined temperature or higher (see Japanese Laid-Open Patent Publication No. 2005-332970).